S/P Ratios of Various Light Sources

New file 2/15/2010, updated slightly 2/27/2016

I have found some published s/p ratios of some light sources to be incorrect.
Many incorrect figures appear to me to be incorrectly low ones stated by
proponents of one or two particular light source technologies competing against
others whose s/p figures were incorrectly stated.

In addition, I have found lack of published s/p ratios of some light
sources where this is of interest.

As a result, I have added a chart of what I believe to be correct s/p
ratios of many light sources, with sources of data/"data". Much of this data is
from questionable to low-traceability measurements, from measurements that I
can trace but requiring adjustments whose properness I was unable to
"properly" measure, from theoretical calculations of some items that are
easy to at least somewhat fairly easy to reconstruct, and from 3
"reconstructions" of high pressure mercury vapor spectral power distribution
that I hope I did a good job of pulling out of my hat. Few of these figures are
from spectral data that I have both actually seen to extent of knowing whose
spectrometer was used and found to not require "adjustments" for clipping,
noise, or other factors.

Note 3: S/p ratios of these white LEDs was calculated from data from a
StellarNet spectrometer, with no adjustments other than the spectrometer
software's calibration data for achieving flat spectral response.
Calculations used all wavelengths 380 to 780 nm in .5 nm increments,
using the 1988 photopic function.

Note 4: S/p ratios of these fluorescent lamps was determined as above in
Note 3, except the spectral data files produced by the spectrometer software
were adjusted afterwards. The strongest two spectral lines were clipped by
the spectrometer or its software. Since the spectrometer is not mine and I
was not able to get re-takes, these spectral lines were manually increased
in intensity in my files until chromaticity as reported by spectrum
analysis software appeared reasonable to me.

Note 5: S/p ratios of these red LEDs was determined as above in Note 3,
except the spectral data files produced by the spectrometer software were
adjusted afterwards. In wavelength ranges where the data was mainly or
effectively exclusively upward spikes of spectrometer noise, the data was
manually reduced to zero. After that, the "tails" of the LED's spectrum
were manually extrapolated as exponential functions of wavelength, outward
in both directions until insignificant, varying exponentially with wavelength
at the same rate as within "each of the notable tails", as best as can be
estimated, from the portions of these "tails" that outweighed the
spectrometer noise. Less care was taken at longer "essentially-infrared"
wavelengths for this adjustment.

Note 6: These "reconstructed" spectral power distributions of high pressure
mercury vapor lamps are "reconstructed" into a file type that I can analyze
from 380 to 760 nm from how I remember high pressure mercury vapor spectra.
These are adjusted to make chromaticity and color rendition effects making
sense. These are not actual measurements and they are "merely out of my hat".

Note 7: These figures for GE triphosphor T8 fluorescent lamps are from page 4-32
of a GE fluorescent lamp catalog that I found at (now at web.archive.org):

Note 8: This item has s/p ratio that appears to me as somewhat of an outlier to
the high side of a trend, although a few lamps of this item type do achieve s/p
ratio so high. I expect 50W high pressure sodium lamps to usually have a lower
s/p ratio around .5 to .55 (updated 2/7/2016).

Note 9: The deep red LED item actually tested here is a GaAlAsP red LED model
that I chose for having a deeper / more-pure color of red than average for
these deep red LEDs. I expect s/p ratio of most GaAlAsP and similarly deep
red LEDs to be around .020-.022 without filtering, and around .016-.0165
with a Wratten 92 or Schott RG630 filter.